Condensation and black mould

Condensation is possibly the biggest cause of misdiagnosis of rising damp and is far more common than rising damp as it is becoming an increasing problem in both modern and older properties.

Condensation happens when air cools down and can't hold its moisture anymore and when this air hits a cold surface, it deposits water molecules as droplets. For example, boiling a kettle near a window produces steam that condenses into liquid on the cooler window surface.

Condensation will most commonly occur overnight as the air temperature of a property will generally drop as people most people will turn their heating off when they go to bed. This is often compounded as many people will shower just before going to bed, increasing the amount of moisture in the air which increases the likelihood of condensation forming on cold surfaces as a property cools overnight.

Black mould will only form on areas that are suffering from condensation as it requires pure water to grow; damp areas that are caused by rising or penetrating damp (i.e. leaky guttering) will contain various salts that prevent black mould from germinating. Research indicates that black spot mould can form very quickly and that mould spores can germinate within days in locations where condensation is occurring.

Simply cleaning black mould with bleach or a proprietary black mould remover containing bleach as this will only remove the colour from the mould, not remove the mould itself. White vinegar is the ideal product to use, and it’s natural so you are not introducing more chemicals into your home!! This is not a solution though, ultimately the source of the condensation must be identified and removed or managed.

At Orchard Home Surveys we will identify areas of black mould in a property, determine the causes, assess why moisture levels are elevated, and advise on managing these levels. It is fair to say that everyone uses a house differently and that different activity within it will cause different environmental changes; for example, a retired couple in a traditional three-bedroomed house are unlikely to generate the same amount of atmospheric moisture as a family with two teenage children! In this (rather extreme) example, the same property, but with higher occupancy and a different usage pattern, is at much higher risk of black mould forming and will need to be managed differently.